Electric circuit protector



July 26, 1938. 11 RlVERs 2,125,126

ELECTRIC CIRCUIT PROTECTOR 7 Filed Sept. 1, 1957 2 sheets-Sheet 1 3Wye/flak Du/"Ward 6. Ewe/'13 M25. m x, 47% for/152%? July 26,, 1938. Di5 v g 2,125,126

ELECTRIC CIRCUIT PROTECTOR Filed Sept. 1, 1957 2 Sheets-Sheet P PatentedJuly 26, 1938 UNITED STATES PATENT OFFICE ELECTRIC omcm'r rnorao'ron'Durward S. Rlveranlndianapolis, Ind. Application September 1, 1937,Serial No. 181,3 3;

' Claims. (c1. zoo-415.5)

quired degree of accuracy, and which may be' reset without having toreplace parts after the overload condition has been removed.

Another important feature of the invention is that the protecting devicemay be present in every extension cord in series with the common linkfuse.

. Further important advantages of the invention are to be found in thesmall and compact structure and particularly in the unique combinationof these various elements as set forth in the appended claims.

These and many other objects and advantages of the invention willbecomeapparent to those versed in the art in the following description of theinvention as illustrated in the accompany-- ing drawings in which:

Fig. 1 is a side elevation in partial section of the plug adapterembodying the invention;

Fig. 2, a top plan view in partial section;

3, a transverse section on the line 3-3 in Fig.

Fig. 4, a section on the line 4-4 in Fig. 1;

Fig. 5. a central longitudinal section through the cord plug embodyingthe invention;

Fig. 6, a similar section on the plane 90 degrees from that 01' Fig. 5;

Fig. 7, a transverse section on line 1-1 in Fig. 6; and o Fig. 8, atransverse section on line 8-8 in Fig; 6.

Like characters of reference indicate like parts in the various views inthe drawings.

Referring to the drawings, the structures are shown on an enlargedscale.

Referring first to the form oi the invention as illustrated in Figs.1-4, a body I. is formed from some suitable insulating material to havean enlarged head ll, herein shown as being slotted in two directions 90degrees apart across its outer end. A terminal prong I2 is attached tothe body ill by its inner end by means of the screw ii to have the prongl2 carried within one of the slots through the head II and extendingtherebeyond. Between the head 01 the screw l3 and the prong l2ispositioned a foot of the contactor is. This contactor l5 extendsrearwardly along the body Ill to bend thereagainst in a yielding mannerwithin the groove l6 formed along that side of the body It). Therearmost end 0! the contactor I5 is turned outwardly so that theconnecting prong 5 I1 01 the connecting plug (not shown) may be insertedbetween the contactor l5 and the side of the body In within the grooveI6. I

On the opposite side of the body In a prong I8 is carried in parallelrelation to the prong l2 and 10 is mounted on the body In by extendinginwardly through the head H and having a foot l9 turned at right anglesto abut the outer end of the body l0 within the transverse slot acrossthe head II. The side slot through thehead ll prevents turnmg of theprong l8 and a rivet is passed entirely through the body l0 axially tobe headed by one end over the root is and by the other end within theslot in the rear end of the body.

Between the rear head of this rivet 20 and the 20 body is secured an end01 a bi-metal strip 2| which is carried laterally from the body l0, Fig.1, and

thence is bent around to be substantially parallel withthe body It) andis carried iorwardly' through .the longitudinal slot in the head H toterminate in a hooked end 22.

On the opposite side of the body II! from the strip 2| is anchored atoot of'the spring 23 by means of a screw 24. This spring 23 is carriedforwardly through the longitudinal slot in the head I I and is bentaround and across over the end slot in the head to terminate by arounded end normally engaged under the hook 22 of the i bi-metal 2|. Thestrap 25 is interposed by one. end between the screw 24 and'the spring23 and is carried around the body ID to the side thereof oppositeto thescrew I 3 where the screw 26 passes through the foot of the secondcontactor 21 and through the strap 25 to engage the body ID.-

This contactor 21 is similar in shape to the contactor I! and yieldinglypresses against the'side of the body -Il within the groove or slot 28into which the second prong 29 in the connecting plug (notshown) isengaged undenthe contactor 21. Thus it is to be seen that an electricalcir- 4 cult is established between the contractor 21 and the prong I!through the strap 25, spring 23, bimetal 2| and the rivet 20.

In order to enclose the structure above described, an insulating housing30 is provided to receive the body II and the head H. The housing 30 isprovided with a pair of slots 3| and 32 through which the prongs l1 and29 may be inserted through the end of the housing to be engaged with thecontactors as" above explained.

the detents on its outer face, whereby the body l and the parts mountedthereon are firmly supported by the cap 34 when this cap 34 is pushed inthe counterbore in the housing 30 and-seated B8 e H. r diameter of thecap 34 made to be such that there is a pressed fit between the cap andthe wall of the housing so that the cap 34 will be firmly retainedthereby.

' The thickness of the cap 34 and the position of the shoulder 33 are.madeto be such that there is a substantial distance left within theouter end of. the housing beyond the-outer face of the cap. This spaceis provided for travelof the reset button 31 which slidingly passesthrough the cap 34 in the path of the spring 23; The button 31 isprovided with a head 38 on its inner end to limit the outward travel ofthe button.

The bi-metal. 2| is selected as to composition, shape and size to carrythe normal full rated capacity of the circuit without distortion.However, when the circuit fiow exceeds that predetermined figure, thebi-metal 2| will bend 'by its hook end away from the body l0 and towardthe wall of the housing 30 so as torelease the end of the spring 23 andthereby break'the circuit. When the spring 23 is released, its free endwill tend to move toward the cap 34 and will therefore pushthe button 31outwardly and give indication of an open circuit.

Before the circuit can be re-established, the adapter must be removedfrom its receiving socket or. attaching plug, in ordei that the button31 may be pushed inwardly to re-engage the spring 23 with the bi-metalend 22. By the time the adapter has been removed for this operation, thebi-metal 2| will have been cooled sufficiently to have returned to itsoriginal position for spring engagement.

The adapter, of course, will be used in -the circuits which are normallyfused at some distribution point and the opening of the circuit in theadapter is preferably made to be such that the circuit will be broken'inthe ada'pter'at a lower current flow than will blow out the fuse at thedistribution point.

Where the circuit protector may be used directly by connecting'it on theend of the ex-. tension-cord, the structure shown in Figs. -8 isemployed. In this form there is a body 40 which carries along one sidethereof a terminal prong'4i, passing through the slot in the headportion 42 so that the single terminal screw 43' will retain the prong4| inpositlon bypassing through the inner end of the prong into .thebody. One of the wires 44 ofthe cord is secured against the prong M bythe screw 43.

Along the opposite side of the body 40 and extending through the slottherealong is positioned the other terminal prong 45 which has a foot 46turned over onto the inner end of the body 40. The strip of the bi-metal41 is connected and interposed between the foot 45 and the securingscrew 48 which passes through the strip and foot to engage the body 40.This -bimetal strip 41 is carried laterally from the foot 4 body 40 bythe attaching screw 52.

50 extends forwardly into the transverse slot 43 a distance and then isbent around to extend freely through the longitudinal slot on the sideof ,the body 40 to terminate by the hook end 49 within the transverseslot across the outer end of the body 40.

On the side of the body opposite the slot carrying the bi-metal 41, iscarried a spring 50 under the terminal plate 5i whichis secured to theThe spring across the end of the body 40 to have the rounded endnormally engaged under the hook end 49 of the bi-inetal. 'The other wire53 of the cord is electrically connected to the plate 5i by means of theterminal screw 54.- Thus the circuit is established between the wire 53and the prong '45 through the spring 50 and the bi-metal 47.

An enclosing housing 55 is provided to receive the wires 44 and 53through the opening in one end. The cap 56 closes the other end'of thehousing by frictional engagement within the counterbore thereof. Thiscap 56 is slotted and permits the prongs 4| and 45 to extendtherethrough, and in the same manner as described above, the prongs 4|and 45 carry the respective detents 51 and 58 to bear against-the outerface of the cap 53 as means to hold the body 40 snugly against the innerface, the reset button 59 slidingly passing through the cap 56 andhaving a limiting head 50 on its inner end. The head 60 is in thepathof-the spring 50 whereby the button 59 will be moved outward asindicated by dash lines when the circuit is interrupted by the movementof the bi-metal 4'landwhereby the spring 50 may be restored toengagement with the bi-metal by pushing in on the button.

While I have herein shown and described my invention in the form as nowbest known to'me, it is obvious that yarious structures may beemployed'without departing from the spirit of the invention and Itherefore do not desire to be limited to that precise form beyond thelimitations imposed by the following claims.

I claim: 1. In a circuit protector, a body carrying a pair of terminalprongs, means fixing said prongs in alignment on said body, athermostatic metal strip carried by the body, a spring actuated membercarried by the body and normally releasably engaged with said strip inseries relation with one .of said terminal prongs and a connectingterminal, whereby the circuit may be interrupted upon distortion of thestrip through heat from a predetermined current overload to release saidspring from said strip, a housing surrounding the body, a housingclosure supporting said body, an indicating and reset button in the pathof said spring guided and limited in outward travel through saidclosure, said prongs being carried. through said closure, saidhousinghaving aportion projecting beyond said closure in the direction.of saidprongs at least as far as the outward limit-oi travel of said button.

2. In a circuit protector, a body carrying a pair of terminal prongs,means fixing said prongs in alignment on said body, a thermostatic metalstrip carried by the body, a spring actuated member carried by the bodyand normally releasa'niy engaged with said strip in seriesyrelation withone of said terminal prongs and a connecting terminal, whereby thecircuit may be interrupted upon distortion of the strip through heatfrom 2,1'as, 1 as an indicating and reset button in the path of saidspring guided and limited in outward travel through said closure, saidprongs being carried through said closure, said housing having a portionprojecting beyond said closure in the direction of said prongs, at leastas far as the outward limit of travel of said button, said terminalcomprising a spring member yieldingly pressed toward the body, and asecond like terminal spring member electrically connected to the otherof said prongs, said housing having openings arranged to permitengagement of other prongs therethrough with said terminal members,whereby said protector may be used as an intervening adapter between themale and female parts of a standard connecting plug.

3. In a-circuit protector, a body of insulation slotted along one side,a connecting prong positioned in said body slot secured thereto andcarrying a terminal, said body being provided with a second slot on itsopposite side, a second prong carried in said second slot and having afoot turned over onto the body, means for securing the foot to the body,a thermostatic metal strip electrically connected to said foot andrigidly mounted by one end in relation to the body, said strip beingcarried along a side of the body removed from either prong side, aconductor secured by one end on the body opposite said strip side andcarried therealong to turn in a yielding manner over the body end intoreleasable normal engagement with said strip between said prongs, ahousing about said body, and a housing closure at one end of the housingcarrying said 'body'to have said prongs extend outwardly through theclosure, and a reset button slidingly carried by the closure in the pathoi-said conductor, said housing having a portion extending beyond saidclosure within which extension said button may travel.

4. In a circuit protector, a body of insulation slotted along one side,a connecting prong positioned in said "body slot secured thereto andcarrying a terminal, said body being provided with a second slot 'on itsopposite side, a second prong carried in said second slot and having afoot turned over onto the body, means for securing the foot to the body,a thermostatic metal strip electrically connected to 'said toot andrigidly mounted by one end in relation to the body, said strip beingcarried along a side of the body removed from either prong side, a leafspring secured by one end on the body opposite said strip side andcarried therealong to bend over the body end into releasable normalengagement with said strip between said prongs, a housing, about saidbody, and a housing closure at one end. of the housing carrying saidbody to have said prongs extend outwardly through the closure, and areset button slidingly carried by the closure in the path of saidspring, said housing having a portion extending beyond said closurewithin which extension said button may travel, a detent on at least oneoi said prongs engaging the outer face of said closure whereby said bodywill be firmly abutted against the inner face of the closure after theprongs have been passed through the closure to permit said detent toengage said outer face.

5. In a circuit protector, a body of insulation slotted along one side,a connecting prong positioned in said body slot secured thereto andcarrying a terminal, said body being provided with a second slot on itsopposite side, a second prong carried in said second slot and having afoot turned over onto the body, means for securing the foot to the body,a thermostatic metal strip electrically connected to said foot andrigidly mounted by one end in relation to the body, said strip beingcarried along aside of the body removed from either prong side, a leafspring secured by one end on the body opposite said strip side andcarried therealong to bend over the body end into releasable normalengagement with said strip between said prongs, a housing about saidbody, and a housing closure at one end of the housing carrying said bodyto have said prongs extend outwardly through the closure, and

, a reset button slidingly carried by the closure in the path of saidspring, said housing having a portion extending beyond said closurewithin which extension said button may travel, a detent on at least oneof said prongs engaging the outer face of said closure whereby saidbodywill be firmly abutted against the inner face of the closure afterthe prongs have been passed through the closure to permit said detent toengage said outer face, said closure being a part separate from saidhousing and attached thereto by frictional engagement within a bore inthe housing.

6. In a circuit protector, a body of insulation slotted along one side,a connecting prong positioned in said body slot secured thereto andcarrying a terminal, said body being provided with a second slot on itsopposite side, a second prong carried in said second slot and having aroot turned over onto the body, means for securing the foot to the body,a thermostatic metal strip electrically connected to said foot andrigidly mounted by one end in relation to the body, said strip beingcarried along a side of the body removed from either prong side, a leafspring secured by one end on the body opposite said strip side andcarried therealong to bend over the body into releasable normalengagement with said strip between said prongs, a housing about saidbody, and a housing closure at one .end or the housing carrying saidbody to have said prongs extend outwardly through the closure, and areset button slidingly carried by the closure in the path of saidspring, said-housing having a portion extending beyond said closurewithin which extension said button may travel, ahead on said body atsaid body end having a transverse slot thereacross receiving said bentover spring end thereacross, said metal having a hooked end presented ammwann s. Rrvans.

